Apparatus for drying hops



March 3, 1953 v. A. BLOXHAM 2,630,311

APPARATUS FOR DRYING HOPS Original Filed March 25, 1948 [/2 2o 25 I 4 22 o 3 l]; 5.. Z INVENTOR.

ATTORNEY Var/in ,4. B/ox/mm Patented Mar. 3, 1 953 UNITED STATES PATENT OFFICE APPARATUS :t I J:i-1YING HOIS Vcrlin A. Bloxham, Berkeley, Calif.

Original application March 25, 1948, Serial No. 17,655. Divided and this application May 9, 1950, Serial No. 161,033

2 claims. 1

This invention relates to an app r f y ing hops. The apparatus commonly employed heretofore for drying hops includes a house-like structure having a reticulated floor upon which the hops are loaded. This floor may be some 20 feet above the ground. Beneath the floor is disposed a heater burning fuel of one sort or another. The products of combustion from the heater usually pass through a zig-Zag or similar arrangement of pipes. located perhaps 8 feet beneath the floor on the way to the chimney. Forced draft of air is not provided, but the house is built tall enough. compared to its section. to provide a stack effect.

In order to dry a quantity of hops, the hops are first loaded on the floor to a limit depth of about 24 inches. The heater is then fired up and maintained hot for a sufficient period of time to allow the hops to dry.

There are a great number of objections to this manner of drying, and to the hop drier itself. One of the main objections is the variable quality of the dried product. This variable quality is due to several factors inherent in the process and apparatus. One of the main ones is that dryin is more efiicient in the lower portion of the bed, due largely to the slow passage of air through the bed. The result of this is that if the bed is not turned one or more times durin the drying process, the product will not be unim y dried.

The turning of the hope. in order to overcome lack of uniformity in drying, has its own draw backs. After the hops dry, they becom very fragile and brittle and are easily broken, and when the bed is turned, in order to reverse Dosh tions of the upper and lower layers, many of the cones which have reached the brittle stage will e broken, and the product taken finally jrom the drier will have an excessively high proportion of lines. The labor involved in these extra operations is also objectionable.

As will be apparent from the above description of the hop drier. the hops are subjected to heat by convection from the pipes and also to radiant heat from the pipes. For this reason. though ordinary dry bulb thermometers are customarily used to control the temperature within the bed, the lower layers of hops to which heat is radiated will be at temperatures higher than those indicated by the thermometer. This renders control by the thermometer inadequate and misleading and constitutes one of the reasons for lack of uniformity in the product, since the hop is extremely sensitive to excessive temperature.

Furthermore, this radiant heat raises the temperature of portions of the enclosure which are seen" by the pipes to excessive levels. This results in the successive drying, char-ring and perhaps final combustion of the combustible mate rial, generally wood, employed in construction of the drier. At least the loss of the driers by fire is a common occurrence. f

A further serious objection to the apparatus is encountered in the fact that fines fall from the hops through the door and onto the hot pipes where they become charred and give rise to vapors which in turn ass through the hops and may be condensed on or absorbed by them.

Since the driers are so tall, the difliculty and labor involved in loadin turning, and unloading is considerable. Floor loading is limited to about 24 inches, since heavier loading unduly restricts flow of air. The heater is inefiicient, as much as of the heat going out of the stack.

.An object of the present invention is to provide a novel and improved hop drying apparatus.

The invention includes other objects and features of advantage, some of which, together with the foregoing, will appear hereinafter wherein the present preferred form of apparatus embodying this invention is disclosed.

The apparatus is shown in the drawing, Figure 1 of which is a plan, the enclosure being sectioned below the hop floor.

Figure 2 is an elevation with parts in section.

In the drawin the reference numeral it refers generally to the enclosure or drying house. This house has four walls, as shown, a gable roof, H, a reticulated drying door I 2. and in the apex of the roof an air outlet H. An air inlet 14 is provided above the level of the hops, for reasons which will be prescntlydescribed.

The apparatus for applying drying gas to the house is indicated generally by the numeral 2b. This includes a burner 24, in this instance, a gas burner. a d a blower 22 with its :motor 23. Near the burner 2| is an air inlet 24 which admits air to support combustion of the gas, and also additional air to be mixed with the products of combustion,

Between the blower 22 and house there is provided an outlet valve Dampers 26 may be so operated as o close on the conduit. Within the plenum under the drying door 12 is a plurality of outlets 21 so located and arranged as to secure a maximum of uniformity of distribution of the drying as to the bottom of the floor l2.

A diffuser indicated generally at 28 is used between the burner and the plenum to secure .efiicient mixture of the incoming air with the products of combustion. Suflicient air is taken in through the inlet 24 to mix with the products of combustion and the hot gases so that the temperature of the mixture is within a suitable range. As clearly shown in Fig. 1, the diffuser is made up of a. first bafile 29 positioned directly in front of the burner outlet to deflect combustion products into the path of incoming atmospheric air, a second set of baffles 30 to direct the mixture of air and combustion products inwardly toward a third set of baffles 3| to thoroughly mix the combustion gases and air before the mixture reaches blower 22.

The dampers 26 are used mainly to cut off the flow into the drier whenever this is desirable, as for example, when the apparatus is just being started up and the products of combustion may include smoke or the like which should not be sent through the hops. With the dampers 26 closed and the valve 25 open, the gases may be by-passed to atmosphere.

The opening 14 may be provided at any point under the roof and over the level of the hop bed, but ordinarily on the side of the house from which come the prevailing winds. The purpose of this opening [4 is to allow ingress of atmospheric air to the space above the hops. The air passing through the hop bed evaporates and thus contains a considerable amount of moisture, and in certain stages of the drying, the relative humidity of the air passing from the bed and out the opening I3 may be well up toward 100%. If such conditions obtain for any length of time, moisture may condense on the roof and other exposed and perhaps cool portions of the enclosure. To prevent this, the outside air dilutes the humid air. To this end, the openings 13 are of sumcient size relative to the quantity of air passing therethrough that additional air may be easily forced in by even a slight breeze from the direction which applies pressure to the opening .14.

I have contemplated that a slight aspirating effect may be obtained by the air passing through the bed and through the openings l3 so that openings or louvers [4 need not be in any particular position with relation to the prevailing wind. 7

On the other hand, the dilution of the humid gas by means of outside air is not vital to the process and may be omitted.

In performing the process of this invention, the green hops are first loaded upon the reticulated floor. This may be in conformity with present ractice With the exception that the load may be much deeper, due to the increased efiiciency of the process. This, of course, provides a larger output from a given floor. .The hops will'be ar-'- ranged as uniformly as possible with regard to density and to depth of the bed, which-may generally be in the neighborhood of 45 inches.

Drying is accomplished by blowing mixed air and products of combustion" of the fuel through the bed of hops from beneath under the carefully controlled conditions which will be described hereinafter. Important among these conditions are the velocity of as flow, the moisture content, and the temperature of the gas.

With regard to velocity, I prefer to pass the drying gas through the hops at a velocity of between 25 and '70 feet per minute, since I have found that velocities within this range secure a substantial benefit in avoidance of crushing of the hops in the lower portions of the bed, which is accomplished by thelifting of the hops in the upper portions. With respect to this action, the upper limit of the velocity is that at which the hops will be blown from the bed.

The lower limit of velocity is determined by another consideration. It is important because sufficient velocity insures that the drying gas in the upper portion of the bed will still be able, due to its low relative humidity, to abstract water from the hops in the upper layers. It will be apparent that the slower the air travel, the more likely it is to be saturated before it reaches the upper layers, in which event the upper layers will not be properly dried but might even have water deposited upon them.

With regard to temperature, the temperature may not be above about 145 F., otherwise the hops will be charred or drying may be too rapid. I prefer that the air be at a temperature between and F.

Obviously, the drier the air, the more effectively it will dry the first hops with which it comes in contact; however, if the drying gas be too dry, I have found that it is not possible to dry a substantial bed with a satisfactory degree of uniformity; therefore, I prefer that the air used have a relatively humidity of between about 10% and about 17%.

With the above conditions all met, I am able to dry 2. bed 45 inches thick, and even thicker, in 15 hours, turning being unnecessary and uniformity of the drying being such that the greatest differences between samples are in the neighborhood of from 3%8%. With present proc' esses, a difference of 20% is common.

A surprising thing about my process is the suitability of the mixture of combustion gases and air for drying hops, which are notoriously sensitive and delicate. Those skilled in this art have been very difiicult to convince that hops may be satisfactorily dried with such a mixture. However, a considerable amount of experience has proved that premium hops may be prepared by the use of my apparatus and the performance of the process.

Sometimes herein I have referred to the drying gases broadly as air. It is to be understood that the combustion products of hydrocarbon fuels are included. Such fuels as coal, natural or producer gas, oil, petroleum derived bottled gases, and gasoline are to be used.

This is a division of my application Serial No. 17,655, filed March 25, 1948, now Patent No. 2,510,372.

I claim:

- 1. Apparatus for drying hops comprising an enclosure having a roof, sides and a reticulated hop floor, air inlet means in the sides above the hops, as outlet means in the roof, a horizontally disposed plenum beneath the floor, a plurality of outlets in the sides of said plenum so located and arranged as to secure a maximum of uniformity of distribution of drying gases passing there through, a conduit connected to said plenum and leading to a point outside the enclosure, a blower in the conduit, a burner discharging products of combustion of hydrocarbon fuel into the conduit, diffusing means for mixingatmospheric air with the products of combustion to secure a mixed hop-drying gas at a predetermined temperature, said diffusing means consisting of a first bafiie positioned directly in front of the burner outlet to deflect combustion products into the path of incomin atmospheric air, a second set of battles to direct the mixture of air and combustion products inwardly toward a third set of baffles to thoroughly mix the combustion gases and air before the mixture reaches the blower, an outlet valve between the blower and the enclosure and opening into the atmosphere, and dampers in the conduit positioned between said valve and a point outside the enclosure, whereby the gas flow may be cut off from the enclosure and temporarily blown through the outlet valve into the atmosphere.

2. Apparatus for drying hops comprising an enclosure having a gable roof, sides and a horizontally disposed reticulated hop floor, air inlet means in the enclosure sides above the hops and below the lower ends of the gable, gas outlet means in the roof, a horizontal disposed plenum beneath the floor, said plenum consisting of an elongated, pipe-like structure closed at one end and reaching substantially the entire length of the enclosure, a, plurality of outlets in the sides of said plenum so located and arranged as to secure a maximum of uniformity of distribution of dryin gases passing therethrough, a conduit connected to the open end of said plenum and leading to a point outside the enclosure, a blower in the conduit, a burner discharging products of combustion of hydrocarbon fuel into the conduit, difiusing means for mixing atmospheric air with the products of combustion to secure a mixed hopdrying gas at a predetermined temperature, said diffusing means consisting of a first bafiie positioned directly in front of the burner outlet to deflect combustion products into the path of incoming atmospheric air, a second set of baffles to direct the mixture of air and combustion products inwardly toward a third set of battles to thoroughly mix the combustion gases and air before the mixture reaches the blower, an outlet valve between the blower and the enclosure and opening into the atmosphere, and dampers in the conduit positioned between said valve and a point outside the enclosure, whereby the gas flow may be cut off from the enclosure and temporarily blown through the outlet valve into the atmosphere.

VERLIN A. BLOXHAM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,221 Mayo Nov. 10, 1942 1,224,560 Needham et al May 1, 1917 1,431,213 Braley Oct. 10, 1922 1,999,513 Morrison Apr. 30, 1935 2,223,597 Brewster Dec. 3, 1940 2,444,588 Bossinger et a1 July 6, 1948 2,510,372 Bloxham June 6, 1950 2,541,332 Campbell Feb. 13, 1951 

